Photosynthesis and Water Use Efficiency in Twenty Tropical Tree Species of Differing Succession Status in a Brazilian Reforestation

Leaf gas exchange characteristics were measured in twenty woody species that differ in succession status ranging from pioneer species (PS) to late succession species (LS) in a Brazilian rain-reforestation ecosystem. Photon-saturated photosynthetic rate, calculated per either a leaf area (P_NA) or a dry mass (P_NM) basis, differed among species. P_NA and P_NM were highest in PS and lowest in LS. Variation among species was 3-fold (from 7 to 23 mol m^–2 s^–1) for P_NA, and 5-fold (from 50 to 275 mol kg^–2 s^–1) for P_NM. The highest P_NA (23 mol m^–2 s^–1) and P_NM (275 mol kg^–2 s^–1) values were recorded in PS Croton urucurana, while the lowest P_NA (7 mol m^–2 s^–1) and P_NM (50 mol kg^–2 s^–1) values were recorded in LS Aspidosperma cylindrocarpon. A considerable overlap was recorded between PS and LS in values of stomatal conductance (g_s), transpiration rate (E), and leaf mass to area ratio (ALM). However, C. urucurana also showed highest g_s and E. P_NM was highly correlated with ALM in both PS and LS (r=–0.75 and –0.90, respectively). The high values of instantaneous transpiration efficiency (ITE) and intrinsic water use efficiency (WUE_i) were also observed in the PS when compared with the LS.